


the (unexpected) side effects of really awesome sex (with super soldiers)

by SailorChibi



Category: Marvel Cinematic Universe, The Avengers (Marvel Movies)
Genre: Established Relationship, Fluff, Humor, M/M, Magical Healing Cock, Multi, Polyamory, Sorry Not Sorry, Super Soldier Serum, Threesome - M/M/M, magical sperm, no that's it, that's the story
Language: English
Status: Completed
Published: 2016-05-14
Updated: 2016-05-14
Packaged: 2018-06-08 07:37:17
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,277
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6845182
Author URL: https://archiveofourown.org/users/SailorChibi/pseuds/SailorChibi
Summary: <blockquote class="userstuff">
              <p>"What, that fucking you might give you a bit of the serum?" Bucky drawls. "Can't say we've ever tried it with anyone else."</p>
            </blockquote>





	the (unexpected) side effects of really awesome sex (with super soldiers)

**Author's Note:**

> I found this on my USB stick. I... don't even know. I'm throwing my hands up with this one.

The words don't really register until Pepper's already turned away. She's flipping idly through her tablet, humming under her breath, while Tony looks at her back. Her hair is scraped into a tight, high ponytail, and the ends just tickle the nape of her neck. At one time, when they were more than friends, he would've leaned forward and blown gently on that spot to make her giggle. Now, he runs the words over again in his mind, turns them inside out, tries to make them make sense. It doesn't work.

"What did you say?" he says.

"I said, did you get a new hairdresser? I can't see the grey in your hair anymore," Pepper says, looking up and back. She catches him staring and her mouth twists, eyebrows shooting up. "Tony... you did know you had grey in your hair, right? I mean, you're nearing your mid-forties -"

"I knew," Tony says, cutting her off, because he definitely doesn't need to hear the rest of that sentence. He sits there for a little while longer, jiggling his leg impatiently until she goes back to her tablet. Then he gets up, ducking past her and the hovering flight attendant and into the bathroom. He locks the door and turns to face the mirror.

Even on a private, fully loaded jet, the lights aren't the best. Maybe that makes the difference. Tony stares hard at his reflection and sees... nothing. Well, nothing that screams change. Because it's all subtle. The lines at the corners of his eyes are softer. His skin in general is a little tighter. His hair is darker and a bit curlier, the way it was in his twenties. He leans in closer, checking his teeth and tongue, then examines the rest of his body. He's always been in good shape, but everything is definitely firmer than it was the last time he checked.

Which was... God, Tony can't even remember now. He usually tries to avoid looking at himself in the mirror. It's not that he doesn't look good for a guy nearing the wrong side of the hill, but he doesn't like seeing the arc reactor. It also doesn't help that for the past several months, he's been sleeping with arguably two of the hottest guys walking the Earth. Steve and Bucky are sexy enough to get anyone's engines revving separately, but together the two of them are a force to be reckoned with. A force Tony has gladly gone down under many, _many_ times.

He pauses in the midst of checking his ass out and kind of... stares into space for a while. Which, of course, is exactly when Pepper opens the door and pokes her head in. She sees him standing there with his pants and boxers around his ankles, bent over in front of the mirror, and - to her immense credit - does not scream. Instead, she rolls her eyes so hard it has to hurt and shuts the door quietly, but with extreme force.

Then, through the door, she says, "I told you I didn't want to know intimate sexual details about your new relationship, and that includes visual displays."

Tony grabs his boxers and pulls them up. "Pep, do I look different to you?"

"Do you have pants on?"

"Yes."

She opens the door and looks at him. Really _studies_ him, eyes narrowed critically. "Maybe?" she says at last. "I see you every couple of days, Tony. It's hard for me to tell. Why? Should you look different?"

He looks at the mirror again and chews on his bottom lip. "I don't know."

When the jet touches down, he and Pepper go their separate ways. She's due back at the office, and Tony has a precious few minutes of free time. He heads back to the tower, thinking the whole way. Now that he's noticed that something might be different, he can't let it go. Things that didn't matter a lot at the time - being able to lift slightly heavier weights, or go for a little longer without sleeping, or even the fact that his back no longer bothers him if he sleeps on the couch - are suddenly pointing to a whole new conclusion.

Instead of going to find Steve and Bucky when he gets home, he tracks down Bruce and finds his fellow scientist bent over a microscope. "I need you to do some tests," Tony says without preamble.

"Tests?" Bruce says, not looking up.

"Blood tests."

That gets Bruce's attention. "Are you sick?"

"No. I don't know. Maybe. Can you -" Tony slips his jacket off and extends an arm.

Bruce frowns, but grabs a needle. He keeps a fully stocked kit now, in spite of his protests about not being "that kind of doctor". Smoothly, he uncaps it, slides the needle home, and draws some blood. "What am I looking for?"

"If you find it, you'll know."

The frown deepens into an exasperated expression Tony is intimately familiar with, but Bruce can't resist a challenge. Tony slings himself down into a spare seat and takes out his phone, but spends more time watching Bruce than he does working. So he knows the instant Bruce finds it. Bruce's whole body tenses up and he gasps. It's a very quiet sound, but loud in the otherwise silent room.

"Tony... This is... Do you know what this is?" Bruce turns to face him, eyes wide.

"The serum?" Tony says, and it's amazing how he can feel terrified and exhilarated all at the same time.

"There's trace amounts of it in your system. In your blood. Not even as concentrated as it is in Bucky, but enough to make a difference. Biologically you're probably in your late thirties now. You... how is that even _possible_?"

Tony licks his lips and tries not to think about the hours he's spent on his knees getting fucked by one super soldier while another feeds a gorgeous dick into his willing mouth. Or the days where it's just one after the other, Steve and then Bucky, fucking him over and over until he's to blissed out to function. It doesn't work. He can feel the blood rushing to his face.

The thing is that Tony likes bottoming, and it's not something he did much before he went into a relationship with Steve and Bucky. It requires a lot of trust to make yourself that vulnerable, and a one night stand doesn't exactly lead to that when you're Tony Stark. He's never thought to wonder why Steve and Bucky don't usually fuck each other or want Tony fuck them because it was so good. Even now the memory of the hands on his body makes him uncomfortably hard.

Bruce seems to sense where his thoughts have gone. But, true to form, he looks more intrigued than anything. "Fascinating. I never would have guessed that would be possible. Do you know what this means?"

"I need to have a long conversation with my boyfriends?" Tony says, attempting for levity and falling flat.

The smile on Bruce's face vanishes instantly. "You didn't know."

"I never even guessed. Fuck, Bruce, this is..." Tony shakes his head, because words are failing him and that _never_ happens. "I don't even know if they know. Maybe it's a happy coincidence." Though he doubts that.

"They had to have guessed," Bruce says gently, confirming his suspicion.

Tony nods, folding his arms across his chest. He doesn't know if that makes him angry or not. Because this doesn't change the fact that he likes being fucked. He likes it a lot. And it wouldn't be the same with a condom; it makes Steve crazy to see come trickling out of Tony's hole after a good hard fucking. Just like Bucky loves to fuck him after Steve's already had his turn, when Tony's loose and open and just a little sloppy. Those aren't things he wants to lose.

"I think I need to go," he says, swallowing hard. "Thanks, Bruce."

"We need to run more tests, Tony. Come see me later?"

"I will." And Tony will, funnily enough. Bruce has had enough tests run on him that he knows what it's like to be treated as an object of science first and a human second. He might not be "that kind of doctor", but he's far and above the best doctor to ever treat any of the Avengers.

He heads out the door and takes the elevator up to Steve's floor, which has unofficially become their floor, because he knows it's where he'll find Bucky and Steve. Sure enough, he walks through the door to find his boyfriends cuddling together on the couch. They're disgustingly domestic, really; Steve is laying on his back with Bucky tucked up against him at a perfect angle to exchange lazy kisses. The television isn't even on, but the electric fireplace is and the room is warm enough that both of them are shirtless.

So Tony makes the snap decision to stand there and watch them for a little while without interrupting, because who wouldn't? Steve is always a little more possessive; he likes nipping and biting, even though the marks don't stay on Bucky. He's got a hard grip, like he's making up for all the years when he wasn't strong, and kisses deep. Bucky is no gentler, but he's more protective even in the middle of sex. And he likes to tease. Sometimes those mama bear instincts turn into hours of the slowest sex Tony's ever been a part of.

When the hands start to wander below the waist, Tony clears his throat. Bucky's head pops up immediately, though not without one last, lazy lick to the curve of Steve's jaw. He gives a predatory smile when he sees Tony standing there. His metal hand appears over top of the couch and he lifts up, smoothly lunging his weight over the back. Steve follows, no less graceful even though he stands and rounds the couch.

"Hey," Bucky says, hands reaching for Tony's hips to pull him into a kiss, and Tony has to make himself side step it. Bucky falters, arms falling back to his sides.

"I just saw Bruce. He found something interesting in my blood. Can you guess what he found?" Tony says, trying to keep his voice calm.

It's Steve who gives it away. The man is shit at lying and they all know it, so he doesn't even bother to try. He just goes straight into full on puppy eyes. "Babe -"

"Don't you babe me! Did you know this would happen?"

"What, that fucking you might give you a bit of the serum?" Bucky drawls. "Can't say we've ever tried it with anyone else."

Tony glares at him. 

"Does it upset you?" Steve asks earnestly. 

"I don't know," Tony says, which is at least honest. He really doesn't. They haven't outright discussed his mortality, though they have danced around the subject a handful of times. It openly upsets Steve a lot to think about it and tends to send Bucky into intense periods of silence, so Tony never wants to bring it up. Apparently he should have. He turns away from both of them and walks across the room to pour himself a drink. 

"We're sorry," says Steve.

"We are? Oof!" Bucky grunts. Tony doesn't need to look around to know that Steve just elbowed him. "Fine, okay, we are."

It's impossible to suppress a smile at the complete lack of contrition in Bucky's voice. They're not sorry, not even Steve. And really, Tony is intelligent enough to know this is a just an inevitable side effect of sleeping with two super soldiers. He's the one who first suggested they forego condoms, because he's clean and neither Bucky or Steve are capable of catching anything even if he wasn't, and both of them had asked him at least twice if he was sure. 

This isn't something they _did_ , exactly. They just omitted to share that side effect with him. And he could get angry about it. No one would blame him. Really, as Tony sees it, they've got three options.

Number one. Break up with Steve and Bucky.

Number two. Use condoms from here on out.

Number three... 

He tosses his drink back, savoring the burn. It's good, expensive whiskey, smooth and leaving the taste of honeyed smoke on his tongue. It helps to clear his head a little. He's not sure how he feels about the possibility of an extended life - not great, but is it worth giving up really fantastic sex for?

"You're going to have to make it up to me," he says steadily, forcing back a smile when Steve's eyes light up and Bucky's predatory smirk returns. "Like, think 'MIA on a mission for three days' levels of making it up but scaled up to eleven."

"I think we can swing that," Steve says, sashaying closer, an honest to god swing to his hips, this fucking _man_. He reaches for Tony and this time, Tony lets it happen. He goes as eagerly into Steve's arms as ever, because this is a drug that Tony couldn't break himself of if he tried.

Bucky swings around behind him, until he's sandwiched between the two of them, right where Tony loves it the most. He drops his head back against Bucky's shoulder, looking up at the ceiling as two sets of lips begin kissing his throat, hands roaming his body. Dim as the room is with only the fireplace for light, he can still make out the flecks of paint with ease.

He wonders how this whole super serum thing will affect his stamina.

**Author's Note:**

> Find me on [tumblr](http://tsuki-chibi.tumblr.com/).


End file.
